Pattern-reversal retinal potentials (PRRPs) are bioelectrical signals, generated within the proximal retinal layers, which can be recorded from the cornea of the human eye when phase-alternating stimuli are viewed. Our previous investigations have revealed that PRRP amplitude is significantly reduced in patients with primary open-angle glaucoma (POAG) relative to age-matched visual normals (AMVNs). Furthermore, our results indicate that the magnitude of this PRRP amplitude reduction is greatest when the visual stimuli are phase-alternated at a high temporal rate (i.e. 16 reversals per second). This suggests that the development of POAG produces a high frequency attenuation in the temporal tuning characteristic of the human PRRP. Additionally, we have noted that patients with ocular hypertension (OHT) and elderly visual normals (70-79 years of age) may exhibit PRRP amplitude reductions for high temporal frequency stimuli. These observations suggest the following three hypotheses which will be tested in the proposed investigation: 1) Reductions in PRRP amplitude provide reliable prognostic indications of which ocular hypertensives will develop POAG (a longitudinal study), 2) PRRP amplitude is significantly reduced in patients with low tension glaucoma (a cross-sectional study) and 3) normal physiological aging produces progressive reductions in PRRP amplitude (a cross-sectional study).